Conversion of dimethyl ether



Dec. 14, 1948,

.Summum v .rw m M .N m .0 .IIIMHl W m m 4 T 0 G m 0/ M Nm G T S? ww n T u u v w. M N mw mw a S E M w n. o? NQ. Sv N mw l] R S. u 55% MSN SL .3M \Sv mw ww n@ R, n@ n.

.ww Nm E v N N 'www nlug 3565.@ .Q @ms N I8. mm N vn @n wn 2 www* nn N wh; mwwwhrw N@ D2 am @q @S R @mi Q EN w91 F NWS m vwf Hww @Ts 4 mm mw\\ .$6 mago,

Patented Dec. 14, 1948 CONVERSIONOF DIMETHYL ETHER Everett Gorin, Woodbury, N. J., and Manuel H. Gorln, San Francisco, Calif., assignors, by mesne assignments, to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New York Application November 18, 1946, Serial No. 710,476

8 Claims. (Cl. 260-668) This invention relates to the conversion of dimethyl ether to normally liquid hydrocarbons. More particularly, this invention relates to a process for the conversion of a mixture of dimethyl ether in the presence of a predominantly isobutane diluent to a mixture of normally liquid hydrocarbons predominantly of the isoparainic and aromatic types.

Various methods of producing normally liquid synthetic alumina catalyst or synthetic aluminasilica catalyst. The conversion is preferably l carried out in the presence of isobutane diluent to obtain a high yield of normally liquid hydrocarbons. Dimethyl ether may be readily prepared in high yields from methanol intermediate by catalytic dehydration. Dimethyl ether may also be produced directly from synthesis gas by the choice of a suitable catalyst although more hydrocarbons syntheticallyvare known to the art. i or less methanol will be produced simultaneously. Probably the most commonly known method is Since methanol may be readily produced from the catalytic hydrogenation of carbon monoxide synthesis gas, obtainable by the reaction of steam and the simultaneous condensation of the hydrowith natural gas or coal, or by partial oxidation carbon product to normally liquid hydrocarbon of methane, our invention provides an indirect mixtures as exemplified by the Fischer-Tropsch l5 method for the conversion of coal or natural gas process. Another method is to chlorinate nort0 Iwrmaliy liquid hydrOCaIbOIiS. mally gaseous hydrocarbons which are then con- The condensation of dimethyl ether is effected verted to liquid hydrocarbons and hydrogen chic with the aid of catalysts which exhibit proride by-products in a thermal condensation renounced polymerization and dehydration activity. action, Such a, process is taught 1n U, S, Patent 20 Metallic OXlde type Contact catalysts Which have 2,320,274.- Various modifications of the former Surfaces Of CidC ChalaCter may be employed method produce highly olelnic, straight chain advantageously for the promotion of the condenhydrocarbons or normal parafnic hydrocarbons sation reaction. Acid-leached alumnas constiof low antiknock value when used as motor fuel. tute 011 type of catalyst which may be used. The The latter process requires relatively high temalumina catalyst may be prepared by leachinr peratures in the alkyl chloride condensation step COmmCICiai activated illumina gel with an organic and also requires corrosion resistant materials of acid $11011 as OrmC acid or acetic acid or with an construction due to the formation of hydrogen inrganic acid such as hydrOuOrc acid. 13h05- chloride byproducts, phoric acid, o1' boric acid. The acid-leached The present condensation process requires only alumina is then dried at 100 C. and reactivated moderate temperatures in the conversion oi diby heating at a temperature 0f about 500 C. for methyl ether to liquid hydrocarbons and no cor- Several hOulS. rosive soy-product 1s formed in the reaction. The g A second group of catalysts which are parliquid product consists primarily of aromatic ticularly effective in our process consists of assochydrocarbons and lsoparainic hydrocarbons suitciations of alumina and silica, which combination able fo;- incorporation in motor fue1 of oxides may also contain one or more oxides of An object of this invention is to provide an metals of groups II. HI. and IV 0f the periodic improved process for the synthesis of normally table such as beryllium oxide, magnesium oxide, liquid hydrocarbons. Another object of the in` boron oxide, lanthanum oxide, zirconium oxide, vention is to produce synthetically a'mixture of 40 and thorium Oxide. It is essential that thek normally liquid hydrocarbons containing a rela- Catalyst GOES 110i Contain Significant quantities tively high percentage of isoparafllnic and aroof oxides of other groups 0f the periodic table. matic hydrocarbons; Still another object of the Alkali metal oxides and other strongly alkaline invention is to catalytlcally condense dimethyl oxides destroy the activity of the catalyst. Oxether to produce normally liquid hydrocarbons ides which show catalytic activity with respect to suitable for incorporation in motor fuel. A furhydrogenation also should be excluded from the ther object of the invention is to catalytically reaction zone. Such oxides as the oxides of condense dimethyl ether in the presence of chromium or molybdenum oxide as well as the isobutane and normally gaseous olenic hydrooxides of metals of the transition group such as carbons to produce high yields of normally liquid iron oxide cause extensive decomposition of the hydrocarbons. y Other objects will be apparent methyl ether to such undesirable products as free f from the description of the invention. carbon, methane, and the oxides of carbon.

We have found that dimethyl ether can be We prefer a catalyst consisting of an associaconverted to hydrocarbons containing two or more tion of silica with a minor amount of alumina. atoms of carbon per molecule in the presence of The catalyst may be prepared by several methods well known in the art. Thus, silica gel, substantially free of alkali metal oxides, may be impregnated with an aqueous solution of an aluminum salt or the silica and alumina may be coprecipltated by the addition of aluminum sulfate solution to a solution of sodium silicate. The precipitate is then washed with water and dilute mineral acid to remove sodium ions from the surface. It is then dried and heated to activate the mixture.

Our preferred catalyst is prepared by ball milling washed moist silica hydrogel with alumina hydrogel, drying the mixture of hydrogels at about 100 C. and activating the mixture at about 500 C. The alumina hydrogel is preferably prepared by forming the alumina hydrosol. A mercury-aluminum amalgam is digested in a dilute solution of an organic acid such as acetic or'formic acid. The clear hydrosol is separated from the amalgam and set to the hydrogel by any of the methods well known in the art. Silica hydrogel may be prepared by the addition of a sodium silicate solution to an excess of mineral acid or acetic acid. The mol ratio of silica to alumina in the finished catalyst may vary from about 5 to 35 mois, preferably from about 5 to about 15 mols of silica per mol of alumina.

The above catalysts are active for the condensation of dimethyl ether at temperatures within the range of from about 300 C. to about 475 C. Temperatures in excess of 475 C. are unsuitable due to excessive decomposition of the products. Our preferred temperature range for operating the condensation reaction in the presence of the alumina-silica catalyst is from about 350 C. to about 425 C. Pressures within the range of from about 50 pounds to about 800 pounds per square inch gage, or even higher, may be used. We prefer to operate the condensation reactor at pressures within the range of from about 150 pounds to about 500 pounds per square inch gage.

When pure dimethyl ether is passed over an alumina-silica catalyst considerable amounts of undesirable by-products such as methane, the oxides of carbon and free carbon are formed. However, Vwe have found that the formation of these products can be substantially suppressed and the yield of liquid hydrocarbons can be substantially increased by carrying out the conversion of the ether in the presence of a diluent. The term diluent" as used in the specification and claims refers to a normally gaseous hydrocarbon containing not more than four carbon atoms-per molecule or a mixture of such hydrocarbons, which hydrocarbons may or may not be reacted under the conditions of operation of the process. At least a part of the diluent may be obtained by recycling the primary reaction products consistlng of Cz, C3, and C4 hydrocarbons. Isobutane is particularly effective in reducing the amount of carbon and methane formed. 'I'he process can be operated under conditions such that no isobutane is consumed or, if desired, sumcient concentration of isobutane diluent may be used to promote alkylation thereof with the ether and/or the light oleflns produced in the process.

When operating our process to avoid consumption of isobutane in the reaction we maintain a mol ratio of isobutane to dimethyl ether in the reaction zone not greater than about 6 to l. Higher ratios up to about 20 to 1 are benecial in suppressing the formation of carbon and methane. The higher ratios of isobutane to ether produce a corresponding increase in the amount oi' normally liquid hydrocarbons in the product and an increase in the isobutane consumed as a result of the alkylation reaction. Preferably, a ratio of at least one moi of isobutane to one mol s of dimethyl ether feed to the reaction zone should be present in the reaction zone.

It is advantageous to recycle the normally gaseous hydrocarbon produce having two or more atoms of carbon per molecule which consists of C2, Cz. and C4 olens and paraiflns. The olennic content of these fractions tends to increase with increasing temperature, and tends to' decrease with increasing pressure and/ or percentage conversion per pass. For economic reasons, we prefer to operate with space velocity, temperature and pressure adjusted to give a relatively high conversion of the dimethyl ether per pass, that is, from about 70 per cent to about 95 per cent or even higher. Space velocities should be adjusted to a value within the range of from about 1 to 40 volumes of total feed per volume of catalyst space per minute when operating at temperatures 0i' from about 300 C. -to about 475 C. and pressures of 50 to 800 pounds per square inch. When operating with our preferred alumina-silica catalyst at temperatures in the range of from 350 C. to 425 C. and pressures of from 150 to 500 pounds per square inch, space velocities within the range of from 3 to about 20 volumes of total feed to the reactor per volume of free catalyst space per minute should be used. The volume of total feed is dened as the volume of dimethyl ether plus isobutane diluent and recycle gas. other than isobutane, measured as a gas under standard conditions of temperature and pressure. Total feed also includes any methanol present in the feed to the process.

As indicated hereinabove the chief source of dimethyl ether feed to our process is from methanol. The decomposition of methanol to form dimethyl ether produces an equilibrium mixture containing about to 95 mol per cent dimethyl ether and 5 to 15 mol per cent methanol, depending on the temperature employed. We have found that methanol in the presence of isobutane diluent can be converted directly to 02+ hydrocarbons in the presence of the alumina-silica catalyst. proceeds more slowly and the yield of normally liquid hydrocarbons is much lower than is obtained when dimethyl ether is condensed in the absence of methanol. We may use up to 20 mol per cent of methanol in the dimethyl ether feed to the process, although we prefer to first separate the methanol from the dimethyl ether when obtaining the ether feed by the dehydration of methanol intermediate.

The invention will be more clearly understood from the following detailed description of one embodiment of our invention illustratedby the drawing which forms a part of the specification.

Referring now to the drawing. towers 1 and 2 -contain alumina gel-silica gel catalyst either as a continuous bed or disposed in trays. We prefer the latter method of packing these towers, since the difficulty of controlling regeneration temperatures is reduced if the catalyst is maintained in a series of relatively shallow beds. Towers land 2 are manifoldedl in such manner that while one of these towers is on stream for the condensation reaction the catalyst in the other tower is available for the regeneration, thus providing for substantially continuous operation. y

, Liquid dimethyl ether which may contain up However, the conversion of methanoll to mol per cent of methanol is introduced to the p'rocess through line I0 by means of pump II in line I2 which connects with line I0. Isobutane diluent is introduced to line I2 from line I3 and the mixture is passed at a pressure oi' from about 150 pounds to about 500 pounds per square inch through lines I6 and I8, and heat exchangers I5, I1, and I9 wherein heat'is absorbed from the reaction product in lines 25 and 26 and from hot regeneration gases in line 21. From exchanger I'9 the hotfeed passes via line 28 to manifold line 30 provided with valves 3l and 32 and connected with reactor feed manifold lines 33 and 34. With valve 3I in line 30 open and valve 32 closed, the vaporized feed mixture is introduced to tower I through a multiplicity of valved feed lines leading from line 33. By introducing the feed stream to reactor I as a multiplicity of streams we avoid a high instantaneous concentration of the dimethyl ether at any one point in the reaction zone and thus direct the reaction toward the formation of normally liquid hydrocarbons. The temperature of the reaction mixture as it enter-s the reaction zone is within the range of from about 350 C. to 425 C. and the space velocity as defined hereinabove is adjusted to react at least 70 per cent of dimethyl ether per pass through the reaction zone.

'I'he dehydration-condensation of dimethyl ether is a mildly exothermic reaction. Hence, we introduce at least a part of the diluent to reactor I in the form of a relatively cold gas consisting of a major amount of ethylene and minor amounts of methane and propylene. This recycle gas is introduced from line 35 which joins manifold line 36. Line 36 is provided with valve 31, which is open for transfer of diluent, and with valve 38, which is closed.

The product from reactor I consists substantiolly of a mixture of ethylene, propylene, propane, isobutane, normal butane, normal butylenes, nor.- mally liquid hydrocarbons, water vapor, a small amount of unreacted dimethyl ether together with small amounts of methane, hydrogen and carbon monoxide. A small `amount of methanol may also be formed by reaction of the ether with the water poduct. The poduct is passed through drawoil' line 40, equipped with valve 39 which is closed, to manifold line 4I which is equipped with valves 42 and 43, the latter being closed and the r former open for delivery of the product to line leading to heat exchanger I1. In heat exchanger I1 the product is subjected to initial cooling. From exchanger I1 the product passes via line 25 to exchanger I5 where the product is further cooled by heat exchange with the feed. The product passes from exchanger I 5 via line 44 to cooler 45 wherein it is condensed to a mixture containing liquid carbons of less volatility than methane. The condensed mixture also contains dissolved unreacted dimethyl ether and methyl alcohol and water. The mixture and uncondensed methane, carbon monoxide and hydrogen pass from cooler 45 through line 46 to settler 50 wherein the uncondensed components and water are separated from the liquid hydrocarbon components of the product.

Sattler 5D is provided with valved gas release line 5I for the elimination of hydrogen and at least a part of the carbon monoxide and methane from the product. Generally, the amount oi these products in the product mixture is small, partcularly where a relatively large amount of isobutane diluent is incorporated in the feed.

The amount of water vapor produced in reactor I by the dehydration of the dimethyl ether is cotisiderable and hence/the water phase in settler 5|! will contain a considerable part of the unreacted dimethyl ether and also a major part of any lunreacted methanol. isettler through drawoff line 52 and the dimethyl ether and methanol dissolved therein are recovered by fractionation and recycled to line I'0.

The non-aqueous liquid product in settler 50 is passed to heater 53 by means of pump 5 4 in line 55 and thence through line 56 to fractionating system wherein the normally gaseous, predominantly olefinic condensation products and isobutane diluent are separted from the liquid hywrocarbon product of the condensation reaction. Fractionation system 60 may consist of one or more than one fractionator which may be operated to include the normal C4. hydrocarbons in the normally liquid hydrocarbon stream. However, we prefer to include these C4 hydrocarbons in the recycle stream to the reaction zone and to eliminate them with the product streamonly when `the normal butane in the recycle stream builds up to an undesirable concentration. Generally, the normal C4 hydrocarbons are included in the overhead normally gaseous product stream since the amount of normal butane in the product is relatively small and the butylenes are preferably recycled to the reaction zone `where, in the presence of isobutane, they react to increase the yield of normally liquid hydrocarbons.

The liquid product from fractionation system 66 is Withdrawn through valved line 8| and is passed to additional processing steps for the production of motor fuel.y The remainder of the product consisting of normally gaseous hydrocarbons and any unreacted dimethyl ether passes overhead from fractionation system 60 through line 62 to condenser 63 and thence through line 64 to reflux accumulator 65. The gaseous product in accumulator 65 consisting substantially of C2 hydrocarbons, a minor amount of propylene, and any residual methane passes overhead through line 66. This product may be eliminated from the -system through valved line 61. We prefer to recycle the vapor stream through valved line 35 by means of compressor 68 since the ethylene and propylene content of the stream constitutes valuable diluent for the production of increased yields of product in reactor I'.

The liquid product from accumulator A65 is picked up by pump 10 in line 1I and a part of the stream is passed through line 12 to fractionation system 60 for use as a reflux. The remainder of the condensed product is directed through line 13 and at least a part of the stream is recycled via valved line 14 to reactor feed line I2. A part of the condensed product in line 13 may be directed, either continuously or intermittently, through valved line 15 to depropanizer 80 wherein that part of the product of lower volatility than the C3 hydrocarbons is separated from the C3 hydrocarbons. The less volatile stream of hydrocarbons consisting substantially of a major proportion of isobutane and a minor amount of normal C4 hydrocarbons and which also may contain a small amount of unreacted dimethyl ether, is withdrawn from depropanizer through line 8| by means of pump 82. At least a part of this stream may be withdrawn from the process through line 83 to avoid excessive buildup of the C4 hydrocarbons in the System. However, we prefer to recycle the stream through line 84 to isobutane feed line I3. The overhead product from depropanizer consisting substantially of Water is withdrawn from y propylene and any residual ethylene passes overhead through line 85 to condenser 86 and thence via line 81 to reilux accumulator 90. Condensed propylene and ethylene in accumulator 90 are removed therefrom by means of pump in line 92 and are passed in part via line 83 to tower 8s for use as reilux. The remainder of the oleflns is passed through line 9s to line 8s and thence to isobutane feed line I3. Ii desired, propylene and ethylene may be eliminated from the system through line 98 if the concentration of these hydrocarbons in the system becomes excessive. Propane is withdrawn from depropanizer 80 as a side stream through trapout line 98.

After reactor I has been on stream for an interval up to 90 minutes depending on the operating conditions relative to temperature, pressure and amount of dlluent in the feed, sumcient carbon will have accumulated on the catalyst to necessitate reactivation. This is accomplished by passing air through the reactor, the air being diluted with ilue gas in order to control the rate of oxidation and thereby maintain the regeneration temperature below about 650 C.preferably below about 600 C. However, reactor i and the catalyst therein will contain residual dimethyl ether, dlluent in the iorm of gas and residual gases which must be removed before the oxidation of the carbon from the catalyst is attempted. The purge gas may suitably consist of oxygenfree flue gas and/or steam. Ii' desired, themain purging operation may be preceded with a preliminary purge with a dry natural gas consisting substantially of methane and ethane.

Reactor I is isolated for purging by opening valves 38 and |00 in lines 60 and I0| respectively, and closing valve |03 in line |02, valve 3| in line 80, valve 31 in line 36, valve ills in line |05. valve |00 in line |01, valve d2 in line 4|, and valve |00 ln line |08. With valve Ils in line ||5 and valve |88 in line |02 in the open position purge gas is introduced to the system through line IIS and is passed through lines |02 and 36 to reactor i for the removal of residual dimethyl ether and hydrocarbon vapors. Thel mixture of gases passes through line d0 to line I0| and thence from the system.

Afterl reactor has been purged the following valves are adjusted to isolate the reactor for the oxidative regeneration step. Valve iil in line |07, valve 89 in line 40, valve Ii@ in line |02 and valve ||8 in line |05 are closed. Valve I in line ma. valve |08 irl line |07 and valve ||9 in line |20 are placed in the open position. Air diluted with ilue gas is then introduced to the system through line |24 by means of compressor |25 and is passed through lines |05 and 33 to reactor i. Carbon is burned from the catalyst surface and the hot regeneration gases pass from the reactor and from the system through lines 40, |01, 21', and |20. At least a part of the regeneration gas may be recycled to line |24 by adjusting valve il! in line |20 and opening valve |26 in line |21 which connects with line |24. When the reactivation oi the catalyst in reactor I is complete the reactor is again purged with relatively cold oxygen-free flue gas or steam and the reactor is then in condition for reuse in the reaction step of the cycle. While reactor I is on stream for regeneration, reactor 2 is in service for the dehydration-condensation of the methyl ether.

The abovedescription of the process is simply illustrative of the invention and is subject to many modifications by those skilled in the art. Thus, instead ot yusing fixed bed reactors we may use fluidized powdered catalyst in hindered seta tling technique in the reaction cycleor in the regeneration cycle. We may also adapt other methods of catalytic contacting to our process of converting dimethyl ether to normally liquid hydrocarbons. For example, the various types of moving .catalyst bed techniques well known in the hydrocarbon conversion art may be used if relatively low pressure operation is followed. However, we prefer to operate the process at pressures within the range of from about 150 to 500 pounds per square inch in order to obtain higher yields of saturated normally liquid hydrocarbon products.

For the better understanding of our invention the following example illustrating the same is given. It is understood that this example is illustrative only and in no way limits the scope of the invention.

' Exmrxis An alumina-silica catalyst was prepared according to the following method. Alumina gel was prepared by digesting aluminum amalgam in 1% acetic acid to form a clear hydrosol. .The hydrosol was gelled by the addition thereto of a dilute ammonia solution. Silica hydrosol was prepared by the addition of sodium silicate solution to an excess of sulfuric acid solution, the solution mixture being stirred and cooled during the mixing operation. The moist hydrosols were washed with distilled water and then ballmlled together to form an intimate mixture and the mixture was dried at about C. The dried mixture of gels was activated by calcining at about 500 C. for several hours. The nnished catalyst contained 7 mois of silica per mol of alumina.

A mixture consisting of 18.2 mol per cent of dimethyl ether and 81.8 mol per cent of isobutane was passed overv the above alumina-silica catalyst at a temperature of 370 C. and a pressure of pounds per square inch gage and a space velocity of 6.8 volumes of gaseous mixture per volume of catalyst space per minute. The dimethyl ether was reacted to the extent of 94.5 per cent to give a product gas, the analysis of which is given in column two of the table below. The yield of the different products in per cent of the theoretical based on the ether decomposed is given in the third column of the table.

Table CVO. llirt Yoldtler en 0 .f4 Bl'l 0 Component fluent Gas Theoretical Trace 1. 43 5. 7 .3G 10.2 .72 8.1 .37 C; lo .93

`The above results indicatethat 85.7 per cent of the carbon content of the dimethyl ether feed which reacted, appeared in the product as Ca-I- hydrocarbons and that 62.0 per cent of said carbon content was converted to Cu-I- hydrocarbons. There was no significant amount of isobutane produced by or consumed in the reaction.

A similar experiment wherein pure dimethyl 9 ether was passed over the same catalyst at a higher temperature, lower pressure and higher space velocity'resulted in a gaseous product containing a considerably higher proportion of methane and carbon monoxide while the yield of Cs-ihydrocarbons was somewhat less than The yield of free carbon was also quite high when pure dimethyl ether, undiluted with isobutane, was used as feed to the reactor.

This invention is not limited by any theories of mechanism of the reactions nor by any details which have been given merely for purpose of illustration but is limited only in and by the following claims in which it is intended to claim all novelty inherent in the invention.

We claim:

1. The process for the conversion of dimethyl ether to normally liquid hydrocarbons which comprises the steps of (1) passing a feed stream comprising dimethyl ether and a normally gaseous hydrocarbon diluent containing at least two carbon atoms and not more than four carbon atoms per molecule in contact with a dehydration-polymerization catalyst at a temperature Within the range of from about 300 C. to about 475 C. to form a product mixture comprising methane, normally gaseous hydrocarbons containing from 2 to 4 carbon atoms per molecule, normally liquid hydrocarbons, and water, (2) separating methane and water from the product mixture of step 1, (3) fractionating the residual hydrocar-bon product from step 2 to obtain a stream consisting substantially oi normally liquid hydrocarbons and at least one streamof normally gaseous hydrocarbons containing from 2 to 4 carbon atoms per molecule, (4) recycling the stream of normally gaseous hydrocarbons of step 3 to step l, and (5) recovering said normally liquid hydrocarbons from step 3 of the process.

2. The process for the conversion of dimethyl ether to normally liquid hydrocarbons which comprises the steps of (1) passing a feed stream consisting substantially of from about 1 mol to about mols of isobutane per mol of dimethyl ether in said feed stream in contact with an alumina` gel-silica gel catalyst at a temperature within the range of from about 300 C. to about 475 C. to form a product mixture comprising methane, normally gaseous hydrocarbons containing from 2 to 4 carbon atoms per molecule, normally liquid hydrocarbons, and water, (2) separating methane and water from the product mixture of step 1, (3) fractionating the residual hydrocarbon product from step 2 to obtain a stream consisting substantially of normally liquid hydrocarbons and at least one stream of normally gaseous hydrocarbons containing from 2 to 4 carbon atoms per molecule. (4) recycling stream of normally gaseous hydrocarbons from step 3 to step l, and (5) recovering said normally liquid hydrocarbons from step 3 of the process.

3. The process for the conversion of dimethyl ether to normally liquid hydrocarbons which com.. prises the steps of 1) passing a feed stream consisting substantially of dimethyl ether and isobutane in the ratio of at least one mol of isobutane and not more than 6 mols of isobutane to one mol of dimethyl ether in said stream in contact with alumina gel-silica gel catalyst in a reaction zone at a temperature within the range of from about 350 C. to about 425 C. and at a pressure within the range of from about 50 pounds to about 800 pounds per square inch to form a product mixture comprising normally liquid hydrocarbons, normally gaseous hydrocarbons, and

water, (2) separating water from the product mixture oi' step 1. (3) fractionating the hydrocarbons obtained in step 2 to obtain a stream consisting substantially oi' -normally liquid hydrocarbons and at least one stream of normally gaseous hydrocarbons containing from 2 to 4 carbon atoms per molecule, (4) fractionating the normally gaseous hydrocarbons obtained in step 3 to obtain at least one stream of normally gaseous olenic hydrocarbons containing at least 2 carbona atoms per molecule and a stream consisting substantially of isobutane, (5) recyclingl at least a part of each of the oleilnic hydrocarbon iractions and isobutane fraction obtained by step 4 to step 1, and (6) recovering said normally liquid hydrocarbons from step 3 of the process.

4. The process as described in claim 3 wherein the space velocity of the total feed through the reaction zone of step 1 is within the range of from about 3 to about 20 volumes of total gases including the dimethyl ether feed, isobutane diluent and recycle olens per volume of free catalyst space -per minute.

5. I'he process for the conversion of dimethyl ether to normally liquid hydrocarbons which comprises the steps of (1) passing a feed stream comprising a mixture of' dimethyl ether and methyl alcohol containing at least 80 moi per cent of dimethyl ether together with isobutane diluent in an 'amount equal to at least one mole of isobutane per mol of dimethyl ether and methyl alcohol in said mixture through a reaction zone in Contact with alumina gel-silica gelvcatalyst at a temperature within the range of from about 350 C. to about 425 C. to'form 4a product mixture comprising normally liquid hydrocarbons, normally gaseous hydrocarbons, water, and unreacted methyl alcohol, (2) separating water and methyl alcohol from the hydrocarbons vof step 1, (3) fractionating the hydrocarbons obtained in step 2 to obtain a stream consisting substantially of normally liquid hydrocarbons and at least one stream of normally gaseous hydrocarbons, (4) recycling at least a part of the normally gaseous hydrocarbon stream of step 3 to step 1, and (5) recovering said normally liquid hydrocarbons from step 3 of the process.

6. The process for the conversion of dimethyl ether to normally liquid hydrocarbons which comprises the steps of 1) passing a feed stream comprising dimethyl ether and a hydrocarbon diluent containing from 2 to 4 carbon atoms per molecule in contact with a dehydration-polymerization catalyst comprising alumina gel at a temperature within Irhe range of from about 300 C. to about 475 C., (2) condensing at least a part of the reaction mixture of step l to form a mixture consisting substantially of normally liquid hydrocarbons, normally gaseous hydrocarbons, water, and unreacted dimethyl ether, (3) separating water and at least a part of the unreacted dimethyl ether from the mixture obtained in step 2. (4) separating the normally liquid hydrocarbons from the normally gaseous hydrocarbons obtained in step 2, and (5) recoveringr said normally liquid hydrocarbons from step 4 of the process.

7. The process for the conversion of dimethyl ether to normally liquid hydrocarbons which comprises the steps of (1) passing a feed stream comprising dimethyl ether and a hydrocarbon diluent containing from 2 to 4 carbon atoms per molecule in Contact with the dehydration-polymerization metallic oxide contact type catalyst containing alumina gel and silica gel at a temperature within the range of from about 300 C. to about 11 475 C. to react at least 70 per cent of said dimethyl ether. (2) condensing at least a part o.' the reaction mixture of step 1 to form a mixture consisting substantially of normally liquid hydrocarbons. normally gaseous hydrocarbons, watcr. and unreacted dimethyl ether, (3) separating water and at least a part of the unreacted dimethyl ether from the mixture obtained in step 2, i

(4) separating the normally liquid hydrocarbons from the normally gaseous hydrocarbons obtained in step 2, and (5) recovering said normally liquid hydrocarbons from step 4 of the process.

8. The process for the. conversion of dimethyl ether to 'normally liquid hydrocarbons which comprises passing a stream consisting essentially of dimethyl ether in contact with a metallic oxide contact type catalyst at a temperature within the range of from about 300 C. to about 475 C. in a reaction zone to vforni a product mixture containing ,normally liquid hydrocarbons, normally gaseousi hydrocarbons, and water, separating water from the product mixture of hydrocarbons, `and fractionating the hydrocarbons from said (product mixture to obtain `a` stream containing said normally liquid hydrocarbons and at least one stream of normally gaseous hydrocarbons.

EVERETT GORIN.

MANUEL H. GORIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number I Name Date 1,908,190 SchOllkOpf May 9, 1933 2,384,796 Carmody et al. ----4.- Sept. 18, 1945 2,411,578 Lieber et 8.1 1---- NOV. 26, 1943 Certificate of Correction Patent No. 2,456,584. December 14, 1948.

` EVERETT GORIN ET AL. v 4. It is hereby certified that errors appear in the printed specification of the above `numbered patent requiring correction as follows:

Column 3, line 26, for 35 mols, read 30 mols,; column 4, line 8, for the Word "produce read product; column 6, line 15, for hywrocarbon read hydrocarbon; line 54, for as a reflux read as reflux; column 10, line 14, claim 3, for the syllable and Word tions and read tion and;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of June, A. D. 1949.

[IML] THOMAS F. MURPHY,

Assistant O'ommz'asoner of Patents. 

